The role of hamstring tightness in plantar fasciitis.

Background: Plantar fasciitis is a repetitive microtrauma overload injury of the attachment of the plantar fascia at the inferior aspect of the calcaneus. Several etiological factors have been implicated in the development of plantar fasciitis; however, the role of hamstring tightness has not been evaluated.

Methods: Fifteen volunteers (mean age 32.6 +/- 4.7 years) were prospectively analyzed for differences in forefoot loading using a Don-Joy brace (dj Orthopedics, Vista, CA) applied to each knee simultaneously. The brace was locked at varying degrees of knee flexion (0 degrees, 20 degrees, and 40 degrees). Their mean popliteal angle was 6.5 degrees. Fifteen patients (mean age 40 +/- 16.5 years) with a diagnosis of chronic plantar fasciitis were similarly analyzed on the pedobarograph. These patients also had their hamstring tightness evaluated by measuring the popliteal angle. The mean popliteal angle was 23 degrees.

Results: Increasing the angle of flexion from 0 to 20 degrees at the knee joint led to a statistically significant increase in pressure in the forefoot phase by an average of 0.08 K/cm(2)s (p < 0.05). An increase from 20 to 40 degrees led to increased forefoot phase pressure of 0.08 kg/cm(2)s (p < 0.05). The percentage of time spent in contact phase decreased from 35.37% to 30.87% to 26.37% with increasing flexion (p < 0.05). However there was an inverse increase in the time spent in the forefoot phase 46.6% to 55.6 to 61.25% with increasing degrees of flexion (p < 0.05).

Conclusion: The results indicate that an increase in hamstring tightness may induce prolonged forefoot loading and through the windlass mechanism be a factor that increases repetitive injury to the plantar fascia.